Cooking oil is extensively used in the food industry to cook various comestibles. Animal fat or other suitable material may sometimes be used as the cooking material in lieu of cooking oil. The term "cooking oil" is used herein to designate any such material.
Frying is frequently accomplished in relatively deep containers with the comestible to be cooked immersed in the cooking oil. In cases where quantities of food are regularly cooked in such a manner, the cooking oil becomes contaminated with various particles of food or other impurities, and charred food particles produce an odor which adversely affects the taste of foods cooked therein.
Existing commercially-available systems and apparatus for filtering cooking oil require that the cooking operation be interrupted to filter the cooking oil. Wire mesh strainers have long been known and used to remove relatively large particulate matter from cooking oil. Strainers have not been effective, however, to remove sufficient particulate matter to provide particulate-free cooking oil, and have been demonstrated to only slightly prolong the usefulness of the cooking oil. In order to effectively remove and control free fatty acids in the cooking oil, suspended particles of the size of two (2) microns and larger should be removed from the cooking oil.
As presently commercially practiced, cooking oil is cleaned by pumping it through a filter assembly often containing filter paper or other disposable filter element. A filter powder is normally applied to the filter element by dispersal in the cooking oil. This filter powder serves to precipitate particulates and to control odors. Filter powders commonly consist of diatomaceous earth or pearlite. Various other filter powders are used which are made up of various chemical mixtures.
The principal disadvantage of presently practiced methods of filtering cooking oil is that such methods require that the cooking operation be ceased during the period that the cooking oil is filtered. This results in significant down-time.
Filtering apparatus utilizing paper filtering medium require additional down-time due to the necessity of replacing filter elements.
U.S. Pat. No. 4,805,525, issued on Feb. 21, 1989, to the present inventor, describes a cooking oil filtering apparatus which can be used to effectively remove particulates from the cooking oil. This filtering apparatus is inserted within a tank of cooking oil and is generally suspended from the top of the tank. The cooking oil is drawn through wire mesh screens by applying a suction into the wire mesh screens. As the cooking oil is drawn to the wire mesh screens, the screen serves to remove particulates from the cooking oil. The particulate-free cooking oil is then drawn into an outlet and drawn upwardly through the tank to a pumping apparatus. The pumping apparatus will then pass the cooking oil outwardly so that it flows back into the tank and is delivered onto the top surface of the remaining cooking oil in the tank. This process is carried on until particulate matter is removed from the cooking oil. A filter powder is dispersed in the cooking oil to accumulate on the outer surfaces of the wire mesh screens. A Re-issue Application, application Ser. No. 07/813,870 has been filed in relation to the subject patent. The subject apparatus eliminated the need for filter paper. However, it remains necessary with the subject apparatus to discontinue the cooking process while the filtration is accomplished.
Various other U.S. Patents have described cooking oil filtering apparatus. U.S. Pat. No. 4,604,203, issued to Kyle, discloses a cooking oil filtering apparatus and filter therefor using a layered filter formed of a porous web of microfibers and supported by a material more porous than the microfiber web. The filter material which is used is replaced from time to time. U.S. Pat. No. 3,735,871, issued to Bisko, shows a cloth filter jacket for a cooking oil filtering apparatus. The purpose of this apparatus is to provide a jacket which enables cleaning of the filter assembly by scraping. This serves to prolong the time between disassembly of the filter apparatus and replacement of the disposable filter element. U.S. Pat. No. 3,279,605, issued to Shepherd, discloses a filter assembly in which the cooking oil is pumped through the filter assembly. The filter assembly includes a disposable filter medium. U.S. Pat. No. 3,263,818, issued to Gedrich, shows a cooking oil filtering apparatus providing pumping of the filtered cooking oil to its original, or other, container. The filter assembly which is disclosed includes a disposable filter element. U.S. Pat. No. 2,760,641, issued to Miles et al., discloses a portable filtering apparatus providing pumping of the cooking oil through the filter assembly. The filter assembly includes a disposable filter element. U.S. Pat. No. 2,635,527, issued to Overbeck, discloses a deep frying strainer to be located at the bottom of the cooking oil container to strain food particles from cooking oil as the strainer is lifted from the container. The liquid is forced through the strainer by the action of gravity. Although this device is beneficial for the removal of much of the particulate matter, this device does not effectively remove smaller particulate contaminants. Klopfenstein U.S. Pat. No. 2,359,368 , discloses a filter element disposed in a tank containing an unfiltered liquid, for supporting a coating of filtering material such as diatomaceous earth.
Other United States patents depicting filtering and/or straining apparatus include Knight U.S. Pat. No. 445,223, Webb U.S. Pat. No. 2,424,211, Hunter U.S. Pat. No. 2,610,740, Avery U.S. Pat. No. 3,147,220, Wagner U.S. Pat. No. 3,159,094, Holman Pat. No. 3,667,374, Kuether et al. U.S. Pat. No. 4,113,623, Whaley et al. U.S. Pat. No. 4,328,097, and Prudhomme U.S. Pat. No. 4,591,434.
Other publications describing cooking oil filtering systems include:
"New! Permafil Oil Filters;" Filtration International, Inc., Houston, Tex.; date unknown.
"Permafil" Brochure; Edible Oil Division, Houston, Tex.; date unknown.
The Filter Magic.RTM. Sytem by Frymaster Wellbilt Co. Bulletin No. 818-001 Rev 11/86, date unknown.
Re Nu Brochure, Re Nu Vacuum Filter Manufacturing Company, date unknown.
R. F. Hunter Co., Inc. Brochure, date unknown.
Robot Coupe USA Inc. Brochure, date unknown.
Castle Filter Brochure, The Prince Castle Co., date unknown.
Fastfilter.RTM. Assembly and Operating Instructions, date unknown.
Custom Built-In Micro-Flo Oil Filtration, Dean/Alco 11/84.
The patent references and commercial publications do not teach nor disclose a continuous-filtering fryer of the present invention.
It is an object of the present invention to provide a frying apparatus that effectively filters cooking oil during cooking operation.
It is another object of the present invention to provide a frying apparatus that effectively removes particulate matter from cooking oil without the necessity of regular replacement of the filter element.
It is another object of the present invention to provide a frying apparatus incorporating a permanent filter element to provide for relatively efficient and economical filtering of cooking oil.
It is another object of the present invention to provide a frying apparatus requiring relatively infrequent shut-downs for cleaning operations.
It is another object of the present invention to provide a frying apparatus utilizing suction to draw cooking oil through the filtering medium.
It is another object of the present invention to provide a frying apparatus which prevents aeration and splattering of the cooking oil.
It is another object of the present invention to provide a frying apparatus having the filtering element located in the relatively cool area of the cooking oil located below the heating elements.
It is another object of the present invention to provide a frying apparatus in which the filtering element is supported from the bottom of the tank so as to provide for unimpeded access to the top surface of the cooking oil.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.